Simple But Deadly Fuzz(Tonefiend DIY Club Project #2)

I swear, it’s practically worth learning DIY electronics just to build this one insanely simple, insanely great fuzz circuit. What I’m going to call the Bulk Fuzz is a variant on a popular DIY project known as the Bazz Fuss. A really smart guy from Finland named Christian H. figured out how to generate the scuzziest of fuzz tones from a simple transistor/diode pair. It’s a great circuit for modding and custom-tuning, and you’ll have a chance to mix your perfect fuzz cocktail over the course of this fun project.

Incredibly, I don’t know of any commercial manufactures who have co-opted this design. Which means, like they used to say on TV, “Not available in stores!”

Here’s a demo clip. Forewarned is forearmed.

If this sounds like your cup of dirt, please read this great article about the circuit and its variants. (It’s from a cool DIY site, home-wrecker.com/.) Using the techniques introduced in Project #1, you should be able to breadboard any of these and hear how they sound. In the meantime, I’ll be posting a step-by-step project PDF in the coming days. Check back here, or follow tonefiend on Twitter. UPDATE, 11.04.11:The files are here.

yay fuzz!! loving the tone out of the build, i like them both! dare i ask – could we go so far as to throw in beavis’s ‘devolt’ into the build (or as an option), which is essentially a b10k pot along the 9v+, to create ‘volume sag’, and get some more bizarre and beefy sounds?

That’s the nicest thing I’ve heard all day. And it’s been a LOOOOOOOONG day! 🙂

This particular effect isn’t especially great for “wrong voltage” techniques — it’s so simple, it just sort of works or doesn’t, But in any case, it’s always easy to experiment. Just replace any resistor of the circuit with a pot of somewhat greater value, and then dial it down and see if anything cool happens. Then remove the pot from the circuit, measure resistance between lugs 2 and 3, and use a resistor or similar value. Or just keep the pot there are make it adjustable.

Project 1 is done and I’m lovin’ it. Tried the higher gain xistors and came back to the 2N3904. Found a real sweet spot at about 75% volume where I got crystal clear distortion (if that makes sense). No mud.
On to project#2. You have gained another loyal fan.

I know what you mean. IMHO, the vast majority of distortion pedals have way too much gain. If you have a good-sounding amp and guitar, it almost always sounds better to dial back the gain a bit. It’s like the difference between…well, a 2N3904 and a 2N5089. 🙂

For anyone who might be interested: I’ve always been a firm believer that anything worth doing is worth overdoing, and I found a free downloadable schematic drawing software (mine’s for Windows 7) called ExpressPCB, which includes schematic and PCB design capabilities. These kind folks also offer a PCB-burning service, which I haven’t availed myself of (yet), but seems quite convenient. The download is available at http://www.expresspcb.com/expresspcbhtm/download.htm .

If you want to do schematics and board layouts, I highly recommend Eagle PCB:http://www.cadsoftusa.com/
The only differences between the free version and the paid version are that you are limited to 100mm x 80mm boards (still huge, especially for pedals), and your boards are limited to (up to) 2 signal layers.

BroKen- that sounds like a pretty cool resource. $51 for three custom-made boards doesn’t sound too bad, especially for more complicated projects. If I can manage to build the first three here without too much trouble, I may attempt some more complicated things in the future, it would be pretty awesome to have PCBs, seems like once you have the circuit sorted out, stuffing a board would be easier and potentially a bit more idiot-proof than using perfboard for a complicated build.

I use Eagle layout software for two reasons: It’s free (at least the light version is, and that’s all you need for most guitar applications), and it runs on Mac. Gauss-Markov has fine articles on the leading layout programs:

Another thing to explore is etching your own PCBs. Small Bear sells an etching starter kit. It’s messy work, though, and the etching chemicals can be nasty. But it’s WAY easier than you’d ever imagine.

If you get boards fabricated in bulk, they’re MUCH cheaper than buying one-offs. (It’s the same economy of scale familiar to any musicians who has boxes of unsold CDs in their garages.) You can get small boards made for about a buck each — IF you buy 100 or so at a time. Once again, Gauss Markov has a great article about this:

FWIW, I’ve settled into something of a routine with when working with original (or at least semi-original) circuits;

1. Breadboard, breadboard, breadboard. Until it sounds great.
2. Perfboard a a pedal or two, and try them out with different amps.
3. Make a layout in software, and etch a few boards to verify that it works.
4. Spend the $ for a larger run of boards.

I like the sound of IN914 diode and a 3mm red LED. I figured out how to use a toggle switch to change between the two diodes. The IN914 is a lot quieter than the LED. Is there anything you suggest I can do to even out the volume without changing the tone too much or will I just have to live with the boost in volume when I switch between the two?

I’m happy to report that I have successfully breadboarded Project 2, and went with the (2 ea) 1N34a germaniums alongside a 1N914, so I find myself with a nice tonal range as well as a dial-a-growl machine! Everything from buzzy-fuzzy to full-up AARRGHHHH! I’m stoked with this lil guy!
Ken

Hello all, hey did anyone have problems with the pots not changing the sound much. I am a noob, so much so that this is my first project. Version 1 went up without problem, (insert maniacal laughter) and I felt like a mad scientist repeating “It’s alive..It’s alive” Version 2 makes the same sound but the pots don’t shape the sound. Any suggestions? Thanks!

If might help if you post some snapshots of your breadboard or PCB, and maybe some audio clips. I can’t promise I’ll be able t sort it out for you, but maybe “crowd sourcing” can work to your benefit. 🙂

Just to be clear: Are the pots too subtle in their effect? Or do they have no effect whatsoever?

Urgh. My bad. The kit should include one, and I’ve asked Mammoth whether they can add it. Which the probably can.

In the meantime, some solutions:

1. The 47K might work. The value of R1 doesn’t really affect the tone of the circuit — it either works or doesn’t.
2. Any Radio Shack will have a 100K — the most common of all resistor values. Should cost just a few cents.
3. You can always place resistors in series — end to end — for resistance equal to the sum of their values. For example, placing two 47K resistors in series woud give you 94K — DEFINITELY close enough for fuzz.

It was just a test, right? … to see if we are paying attention? I put the 10k in and it is working as of page 10. The radio shack here is getting out of components, but I will buy their “assorted bag” of resistors tomorrow. (I asked there about getting a breadboard and they suggested a kitchen store)

I should have included a bill of materials with the project. Sorry about that! I guess I was thinking that most people would simply purchase the Mammoth kit.

But if you read through the article, you’ll find all the components needed for the circuit. Meanwhile, all the tonefiend project use the same boxing hardware:

• enclosure (they’ll all fit into a small 1590B box, though you can use a larger size if you like)
• stereo input jack
• mono output jack
• 9V DC adapter
• battery snap
• LED
• LED bezel (the hardware that holds the light)
• a 4.7k resistor for the LED
• 3PDT footswitch
• knobs
• hookup wire

Next time, I’ll be sure to include a proper bill of materials right up front! 🙂

One more question – regarding the 22uf electrolytic capacitor for filtering powersupply:
On the Mammoth site, there’s different types, with different voltages and stuff.. does any of it matter as long as it’s electrolytic and has the value of 22uf?

Hi Christopher! The small ones — 16V, for 16 volts — are big enough for stompboxes. A higher-voltage part won’t harm anything, but it’s a waste of space.

Most electrolytic caps are bipolar, which simply means you must be mindful of which wire goes which way in the circuit. This is indicated in the schematic. Most non-electrolytic caps used in stompbox building are non-polar, which means they can go either way.

“Audio grade” is unnecessary, especially if it costs more. In general, the type and quality of capacitor makes little different in these sorts of circuits — no need to spring for some supposedly audiophile item. (Obviously, the part VALUE — the number followed by “uF” — DOES make a great deal of difference.)

You can be pretty casual about this particular part, though. The value can be anything from around 10uF to 100uF. In fact, you could probably even omit it and not hear much of a difference.

Hope that helps!

FYI, I’m preparing a new DIY project, and this time I’m learn from the experience and put a proper bill of materials right up front! 🙂

Cool!
And thank you so very much! You really are a great resource!
Not only do you publish all these free articles on how to build stuff for less than 30$ that’ll easily beat many of the big brand stuff three times the price, but you also have this amazing “customer service”. Nothing but quick replies, and good answers everytime!

I think I can speak for many of the readers of this site when I say this –

Hmmm, if I hook up the tone control as diagramed I get no change in tone. I re read the directions and re installed multiple times. I tried having the .22 on the top and .1 on the bottom and vice versa. Just to clarify on the base bus I should have right leg of .1, neg diode, base, right leg of .22?

If I take lug 3 on the tone pot to ground instead of back to the input I get a very noticable, standard tone knob operation.

Thanks for all of these DIY projects. I went nuts over the last week and built 3 DIY pedals (with mods). Things I learnt:

1. Bad Ass Distortion – using a tone pot between 102 and 224 dials back the extremes of the trebly 102 distortion and the thick 224 tone. The range seems to narrow more (maybe more like a 683 on the high and 104 on the low). Is this because the pot resistor value is too low and hence the extremes are lost due to the capacitors becoming additive in their values? I ended up using a 2P2T switch to switch between 102 and 104. Might change that to a footswitch later. Oh, I really like the 102 distortion – sounds like surf rock.

2. Fiendmaster – I like the germanium-driven oscillations but I can’t get the same kind of tones you got in your demo. I am getting mostly a clean boosted sound with a touch of breakup if everything is on 10. I am suspecting that my amp is not on the edge of dirty. Would this be right?

3. Bulk Fuzz – I messed with the schematics heavily. I got the fiendmaster schematics and placed it in front of the Bulk Fuzz. Fixed values for the cap and resistors for the fiendmaster. Added a pot between two series of diodes for blending. I got an awesome sounding fuzz with tweak-able fuzz types and mad oscillating sustain.

Thanks again for providing hours and days of entertainment. It is now time to get some sleep.

Hey Alex — wow! Thanks for taking the time to tackle all three projects.

Regarding your questions:

1. I don’t quite understand the question. But yes, using a switch instead of a pot is a great alternative. Some boutique Rangemaster, like the Divided by 13 Toneranger, use a rotary pot with a half-dozen caps, like I’ve done in the various Vari-Tone experiments. But I found I was able to get similar results using a pot to fade between a single large and small cap. If you tried the pot and didn’t get the expected results, make sure you have the latest version of the project file — I screwed up something regarding this part of the circuit on the earlier version.

104 is about as large as I’d go for guitar, though I might use a 151 pr 224 for bass. 683 is a real sweet spot to my ear. A 102 is a real thin, rinky-dink sound — not that that’s a BAD thing!

2. While the effect sounds best with the amp turned up a bit, you should hear a pretty dramatic volume boost whereer the amp is set. Try rotating the transistor 180° — sometimes the pinout is reverse from what I showed in my illustration.

3. Yes, yes, YES! Messing with schematics is what this is ALL about. It’s never to early to try doing things the wrong way!

1. What I did was to compare the tone I would get from using a 102 cap alone and a pot between 102 and 224 (with the pot dialed towards the 102). The 102 alone had more treble compared to the pot version. I then read that two caps in parallel are additive and hence thought that it might be that the resistance of the pot not being large enough to prevent the 224 coloring the 102 extreme. Is that your experience too? I think I did have the latest versions of the project files. Oh, you are right about the 224, it is too much for guitar.

3. Ah, you caught me with my poor guitar playing skills. Will see what I can do with my limited skill set. Coming soon.

Well, I pulled everything and started over with the final v3 schematic and the tone is working now. I’m guessing I wasn’t getting a good connection with the board somewhere (cut and restripped all wires) or maybe something was touching. I wouldn’t think the addition of the 1M on the input would make a difference.

I certainly prefer the .22 cap. Gives it the more synth like fuzz tone. The .001 is more of a normal – and good sounding – fuzz. But I’m building this for the crazy synth like fuzz. I may pull the tone control and build in a devolt for the power supply instead.

Wow — thanks for doing that! Awesome job! I love all the illustration. I also tend to agree with your musical analysis of the pedal to. It’s definitely more about loose, anarchic fuzz than tight, palm-muting-type chunk.

I haven’t tackled the Bazz Fuss yet, but I did build a similar circuit I once found that was labelled “One Transistor Distortion/Overdrive.” The biggest differences are that it features back-to-back diodes instead of single diodes and also features a switch to alternate from the current clamp (Bazz Fuss set-up) and shunting to ground on the output (MXR Distortion+ set-up) for further tonal edu-tainment.
After reading this article, I think I’ll mod it out with some of these ideas.
I made a cheesy demo video of it and posted it to Youtube here: http://youtu.be/i7Hq3xDNQ_k

I raided the local electronics store and built the Bazz Fuss and, after I decide on a transistor with the right sound, I’ll mount the pcb in my guitar. Dirty fuzz is fun even if Mommy doesn’t like it at all!

Hi Pierre! Those transistors should work fine, BUT … the pinouts (the order in which the C, B, and E terminals are arranged) varies form transistor to transistor. Just Google “(transistor number) pinout.” It’s probably just a matter of switching your wires to match pin location, or bending the pins to match the wire location. (If you bend the pins, do it gently, ’cause they’re easy to snap off. Also, make sure the don’t touch each other after they’re bend.)

Hey Wyn — are you talking about my demo, or a version you built? And do you mean the high-pass filter effect heard at around 2:45 in the demo? You could get a stronger contrast by using a smaller-value part as the secondary input capacitor. Hope that helps!

So yeah — that would definitely be a thinner sound. Now all, this stuff is subjective, and you may well want exactly that strong a contrast. But just checking: Have you listened to the demo on studio speakers or good headphones? To my (entirely subjective) ear, there’s a lot of contrast as recorded.

But hey — no harm in trying. And worst case, you can swap the cap out again, or maybe just not use the extreme-thin setting very often.

tried a 470 pF and it didnt make much difference to my ears. Its maybe because the more i play around with the tone, it sounds more like it loses voltage. when its full on i get a thick fuzzy sound and full off its i bit more sputtery and the sustains gone. it does sound thinner. Ime no electronics expert so i dont actually know whats going between the 2 caps.i expected it to be more like the tone on my guitar. Think ille just stick with the 1nF. i tried to add a second diode as well. the most significant change was when i put a Ge. diode in reversed. the sound dissapeared on the high tone (1nF) Its still cool with a 3 pot Bazz fuss. maybe ille try the 3 pots with my latest version of the Bazz fuss, and see how it sounds.(its the V3 from homewrecker with an orange diode. sounds really good.heres a pic if your interested.

Hi again….just a little info on the tone pot. I was playing a bit and testing a one knob fuzz up against a big muff and it hit me that the sustain knob on the big muff was exacly like the tone on the bazz fuss. same kind og drop. usefull? maybe..

Thanks so much for these guides, I’m currently building a couple of pedals based on this circuit for my dad and brother for their birthdays.

I’m currently having an issue with the tone caps though. Like Wyn above, when I use a small cap (e.g. 0.001uf) it sounds more like a limiter threshold rather than filtering lows – I have to put a louder signal through the circuit for an output to be heard, which cuts of the sustain. Am I doing something wrong here?

Also like Josh above if I move pin 3 of the tone pot to ground instead of the signal input I get a tone control that I would expect, where I have a 1uf cap on the signal and the 0.22uf cap attached to the pot. Is this a configuration that is sensible to use?

I was using a 2N3094 transistor and thought I’d try a higher gain 2n5088. But I can’t find them here so tried a BC549. But it was hopeless. But I’ve just discovered the CBE pins are reversed! Argh – such a simple mistake.

Oh man, that’s the story of my life, Andrew! I like BC-series transistors, and I’ve used some on my designs. And even with a frickin’ diagram over my workbench showing the proper pinout, I screw this up on a regular basis. I end up twisting the legs till they break off. It feels like I’m torturing insects.